Wireless telegraph and telephone system



Sept. 2 1924.

DE FOREST WIRELESS TELEGRAPH AND TELEPHONE SYSTEM Filed March 20, 1 4 2 Sheets Sheet 1 Patented Sept. 2, 1924.

UNITED STATES PATENT OFFICE.

LEE DI FOREST, OF NEW YORK, N. Y., ASSIGNOR TO RADIO TELEPHONE & TELEGRAPH COMPANY, A CORPORATION OF DELAWARE.

'W'IBELESS TELEGRAPH AND TELEPHONE SYSTEM.

Application filed March 20, 1914. Serial No. 825,954.

To all whomz't may concern:

Be it known that I, LEE 1m Fonns'r, a citizen of the United States, residing at New York, in the county and State of New York, 6 have made a certain new and useful Invention in Wireless Telegraph and Telephone Systems, of which the following is a specification.

This invention relates to wireless tele- 10 graph and telephone systems.

' The object of the invention is to provide a wireless telegraph and telephone system which isisimple and efficient and wherein a provision is made for duplex operationwhether 'for telegraphing or telephoning.

A further object is to provide a more perfect generator of high frequency oscillations of uniform amplitude.

A further object is to provide a system of the nature referred to employing an oscillation generator which combines detector functions with its functions as a generator and to utilize the combined functions thereof for duplex operation.

Other objects will appear more fully hereinafter.

The invention consists substantially in the construction, combination, location and relative arrangements-of parts all as will be more fully hereinafter set forth, as shown in the accompanying drawings, and finally pointed out in the elppended claims.

Referring to the rawings,'

Fig. l is a circuit diagram showing one arrangement embodying. my invention wherein the device serves as a generator of continuous oscillations. I

Fig. 2 is a circuit diagram showing an arrangement whereby thereceiver is not affected by the energy being radiated j from the home antenna.

Fig. 3 is .a circuit diagram showing an arrangement wherein the same device serves as an oscillation generator and a detector.

rate from the 'oscillation generatorifseem plo ed.

1g. 5 1s a similar of a modified form of detector employed in accordance with my invention.

Fig. 4 is 'a' similar view showing a modified arrangement wherein a detecton-sepw' connected in the antenna circuit is an inductance S. The antenna circuit is connected to earth or other capacit 'E, and, where the apparatus is to be use for telephonic communication the antenna includes a microphone transmitter M. Where the apparatus is to be used for telegraphing a Morse telegraph key K is bridged across a portion of the inductance S. The inductance S isin the form of a coil with which is inductively associated, preferably in loose coupled relation, an inductance coil P, one

terminal of which is connected to auxiliaryor cold grid electrodes G, G, arranged'within an evacuated bulb or vessel U. The other terminal of coil P is connected to the cold plates or electrodes W also arranged within the bulb U. Connected across the terminals of coil P is a variable capacity 0,. In series with the coil P and electrodes G, I place a blocking condenser C and if desired, (see. Fig. 3), in series with the coil P and electrode plates W, I place an inductance coil L, across the terminals of which is connected a variable capacity 0,. Contained in the bulb U is a hot electrode F,

which is, in the form shown, a filament or glower, to which current is supplied from any convenient source indicated at A, the current supply bemg regulated by a rheostat R.

As above indicated the current sou-roe A.

may be of any desired form, such for in-' stance as a battery, direct current generator,

or an alternating current generator. Where i an alternating current generator is employed, as indicated in Fig. 5, the frequency,

for wireless telephone operation, should be" above that of the essential frequencies of .voice soundsy'say fifteen hundred cycles per second, or higher. For wireless telegraph work the freqlu bevery much dred per second.

ency of the generator may ower, for example, five hum A telephone receiver T is connected on one side-in s eries with theplateelectrodes .W, and. on the other side 'in se'ries with the filament F. In circuit withthe telephone T, is a source of current supply indicated at B, as a batte r'y, the purpose of which is to impress an electro-motive-forcc between the cold plate el'ectrodesW, and the filament'E By reason of the arrangement above described the device U with its associated electrodes and filaments and their associated circuits and connections, becomes a generator of alternating or pulsating electric currents or continuous oscillations of high frequency in the circuit of coil P, the frequency of which depends upon the spatial relation of the electrode members contained therein, the value of the electro-motive-force impressed across the electrodes, and-the amount of inductance and capacity included in or associated with the circuit of said coil. In the arrangement shown in Fig. 3 the frequency of such oscillations may be varied by vary ing3 the capacity of condensers C or 0,.

y reason of the relation of coils P and S, the oscillations in the circuit of coil P, are impressed upon the antenna-earth system an with a natural period of oscillation in the antenna-earth system the same as that of the oscillations in the circuit of primary coil P.

The amplitude of the oscillations induced in the antenna-earth system as above described may be varied by and in accordance with sound waves falling upon the microhone transmitterM, in the usual manner.

imilarly, a telegraph key associated in the antenna-earth system may serve to control the emission of wave trains in accordance with the telegraphic code, or, if desired, and as shown, ifthe key K is associated with the antenna-earth system in such a manner as to short circuit a portion of the inductance S,

the wave length of the emitted wave trains may be altered in a manner well understood in the art.

It will be seen that, in the arrangement shown in Fig. 3, the device U, with its associated electrodes and filament and circuit arrangement therefore combines within itself the functions of a source of continuous oscillations and also those of a detector, like the audion detector, and its detector functions are in no way impaired by its simultaneous operation as an oscillation generator. Incoming electro-magnetic signals influence the circuits of the electrodes G and W, and produce an alteration in the conducting qualities of the medium between the plate and grid electrodes, and consequently any received signals when attuned'to the proper wave lengt will be heard in the receiver T,

during the pauses between the'signals being made b the 0 ration of the key K, or between t e wor s s oken into the microphone transmitter M. y this simple arrangement, as described, I am enabled to secure duplex operation whether for telegraphing or telephoning, mployin the same apparatus for transmitting an receiving.

It is obvious that provision may be made to protect the telephone receiver'T in case large amounts of current are to pass across the speech the bulb U. Any suitable means may be employed for this purpose, as, for instance the usual high resistance telephone receiver may be employed, which, if desired, may be coupled to the circuit containing the battery B, electrodes W andfilament F, in any suitable or well known manner.

. In Fig. 4 I have shown an arrangement wherein a detector device independent of and separate from the oscillation generator is employed. In this arrangement I employ for the detector an evacuated bulb U, with a filament F and a grid Gr and a plate W similar to corresponding parts above described with reference to bulb U,'the filament circuit being supplied with current from a current source A,, controlled by a rheostat R the plate W constituting one terminal of a circuit which contains the telephone receiver T and current source 13,, the other terminal of said circuit being connected to one side of the filament clrcuit. One terminal of another circuit is connected to the rid G the other terminal of said circuit %eing connected to the other side of the filament F,. This last mentioned circuit is inductively associated with the oscillatingcircuit which contains the coil P, as, for instance, throu h the coils L L the latter being shunted by a variable capacity 0,. By means of the variable condenser C this secondary system can be accurately attuned to the frequency of the received oscillations. It is obvious that-this secondary receiver circuit may be associated with the antenna-earth system, or with the circuit of coil P, in any other suitable or well known manner.

Any suitable means may be employed to supply the necessary inertia to the circult of battery B, such, for instance, as by including an impedance coil I, in said circuit.

Fi 2 shows a balanced antenna circuit associated with the source of the oscillations S, and itsinductances and capacity so proportionedrelative to the capacity of the am tenna itself that the total eflect of the-oscillations from the source S upon the receiver transformer L L is neutralized while at the same time impulses received on the antenna N, preferably of a slightly different frequency from that of the oscillations from S are clearly received in the properly attuned receivin circuit L C, and transmitted to the audion detector U and translated there into telephone currents in the circuit T B in the well known manner.

I am unable at the present time to give a complete explanation of the theory of action of the apparatus when. operating as a generator. I have. discovered, however, as hereinabove-stated, that a system constructed as shown and described and energized from a suitable current source, becomes the.

seat of continuous high frequency oscilla- 'tionsd Undoubtedly the mm 'involved depends upon the e ect of sum sively applied charges or surges of potential upon the grid and plate elements and havmg the power to efiect momentarily the conductivity of the medium between the filament and plate electrodes'in such manner that the current variations in the grid filament circuit reduce corresponding variations in the pllite filament circuit w ich are fed back to the grid filament "circuit to add their effects to the initial variations, which latter, thus reinforced, create and form greater variations in the plate filament circuit which are, in turn, fed back to the grid filament circuit to still further amplify the variations in that circuit, and so on.' The produced which, once set up, are selfer-' petuating, analogous to the whistling or surging action observed when a telephone receiver and microphone transmitter, connected together in the same or coupled circuits, are so placed as to react one on the other mechanically and electrically.-

From the foregoin description it will be observed that in its road scope my invention lies in the discovery that when suitably connected and associated an audion becomes a generator of oscillating alternating or pulsating electric currents w 'ch may be utilized for any urpo'se for which such currents are desired and I have succeeded in securing remarkable results in the practical use and operation of an oscillation generator of this character particularly when applied to the generator of high frequency oscillations. I

It is obvious that the principles of my invention may be embodied in various other arrangements, and that various changes in the details might readily occur to those skilled in the art, and st1ll fall within the spirit and scope of my invention.

But having nowforth the objects and nature of myl invention, and arrangements embodying t e principles thereof, what I claim as new and useful, and of my own invention, and desire to secure by Letters Pat ent, is,

1. Ina system for generating electrical oscillations, a 'work circuit, and means for generating and transmitting the generated oscillations to said work circuit comprising an evacuated vessel having a hot electrode, a cold plate electrode and a cold 'd electrode, an oscillating circuit, one e of said a cold plate electrode and a cold circuit beingconnected to the grid 81am and the other side to'the plate electrode, and

. means for impressing an electromotive-force in the space between the hot electrode and the plate electrode. v

2. In a system for generating electrical oscillations, a'work circuit, and means for generating and transmittingthe generated oscillations to said work circuit com an. evacuated vesel having a hot electrode,

grid electrode, interposed between the hot and cold plate electrode, a source of current for the ot electrode, an oscillating circuit connecting said cold electrodes, and means for impressing an electromotive force between said hot electrode and said cold plate electrode.

3. In a system for generating electrical oscillations a Work circuit, and means for generating and transmitting the generated oscillationsto said work circuit includin an evacuated vessel having hot and cold electrodes therein, circuits for said electrodes, one of said circuits bei a series oscillating. circuit and connecte between said cold electrodes, and means for impressing an electromotive force in the space between two of said electrodes. v

4. In a system for generating electrical oscillations a workcircuit, and means for generating and transmitting the generated oscillations to said work circuit includingan evacuated vessel having hot and cold electrodes therein, circuits for said electrodes, one of said circuits being a' series oscillating circuit and connec between said coldelectrodes, means 'for impressing an electromotive force in the space between two of said electrodes, and a telephone associated with one of said circuits.

5. Means for producing high frequency oscillations for transmisslon comprising a transmitting circuit associated therewith, an oscillatory circuit having two cold electrodes in an exhausted receptacle and a second circuit having a conducting electrode within said receptacle, one of said oscillating circuit electrodes being interposed between the other two, and means for impressing an electromotive force between one of said, cold electrodes and said conducting electrode.

6. Means for producing high frequency oscillations for transmission comprising a transmitting circuit associated therewith an oscillatory circuit having two cold e cotrodes, a conducting electrode, one of said cold electrodes being interposed between the other two, a circuit connection between the conducting and one of the cold electrodes,

vtransmitting circuit associated therewith, an

oscillatory circuit having two cold eleca second circuit includifig g. current source and a conducting electrodeyon'e of said cold electrodes .belng interposed between the other two electrodes, and means for producing a flow of current through the space between said electrodes.

8. Means for generating-high frequency oscillations for transmission inclu a' trodes,

transmitting circuit associated therewith, an

said vessel and separated sel having a-hot' containing hot and cold series oscillation circuit and means for generating and transmittin the generated alternating currents to said work circuit, comprising an evacuated vessel having a hot and a plurality of cold. electrodes therein, said cold electrodes being located at relatively difi'erent distances from said hot electrode, inductance and capacity connected between the cold electrodes, means for impressing electro-motive force in the ace between one of the current .to. the hot electrode.

1 11. The combination with a work circuit, and'means for generating and transmitting the generated-alternating currents to said work circuit, comprising an evacuated vesand a plurality of cold electrodes therein, said cold electrodes being. located at relatively diflerentdistances fromsaid hot electrode, an oscillating circuit' connecting the cold electrodes, means 1 for" impressing. an 'electro-motive force in "the space between the cold andhot electrodes,.-a nd means for supplying current to the hot clec tode.

eleictrodes, aplurality of wing electrod and .a' hot electrode,

motive force between the wing trodes.. 13. In a radio signaling system, anevac- An a-udion halving a plurality of grid es p a series oscillating cir cuit associated with vthegrid and win electrodes, and'means -for impressing an e ectro-' and hot elecuated ves'sel' havingv separated electrodes thereingand'circuit connections therefor to constrtute'a combined generator of high irequnc'y: oscillations'and detector for high ire quency oscillations.

14. In a radio signaling-system, an evacuated vessel having separated electrodes,

therein, and circuit connections thereior to constitutes combinedigenerator of high frecold electrodes'and a sourcecold electrodes and 85; t e hot electrode, and means for supplying cuit's and-electrodes being so a electrical variations in either circuit/produce an electrical variation in the other-circuit.-

eonora quency oscillations and a detector for received high frequency antenna system associated therewith.

15. In a radio si 'aling-system, an evac uated vessel includi hot and cold electrodes therein, said jco d electrodes be' located at relatively difierent distances om said hot electrodes, of said cold electr circuits connecting each es to saudrhot electrode,

and means to set-up successively "increasing" pulsations 'in'said circuits.

16. Ina radio signaling system, anevacuated vessel containing hot and cold electrodes therein, circuits connecting each said cold electrode with saidhot electrode, said circuits being associated, a source of electromqtive force, anda signal indicatingdevice oscillations, and an being'included in said circuits, and an an tenna system associated with said circuits, and means for operatin said signaling system as either a' transmitting or a receiving system.

' 17 In a radio signaling system, an audion including hot and cold electrodes therein, saidcold electrodes bein located at relatively differentdistances rom said hot electrode. circuits connecting each of said cold electrodes to said hot electrode, and means to cause said circuitsto react upon each other.

18. In a radio si aling system, an audion including hot an cold electrodes therein, said cold electrodes" ,bein located at relatively different distances trode, circuits connecting each of said cold electrodes to said hot electr0de,-said circuits being associated to react upon each other.

19. In an electrical system, an evacuated vessel, hot and cold-grid and plate electrodes therefor, a circuit connecting each of said cold electrodes with said hot electrode, said circuits being associated react upon one another. Y

20. In an electrical system,,an'evacuated vessel, a hot electrode within "saidveaael, cold. grid and plate electrodes associated there with, a circuit connecting each of said cold electrodes-with said hot electrode, said cir- 21. In anelectrical system, an audion' including a hot electrode, a

the plate electrode and with said hot electrode, and means for causvariations in the circuit of theplate electrode to react upon the controlling electrode.

In testimon j whereof I have hereunto set niy 'handin't e-pres'enee of the subscribing witnesses, on this 10th day of March A. D.

' LEE on FOREST.

Witnesses-z S, EDwAnn GINSBURG,

.W. A. Dmr.

om said hot electhat I plate electrode a controlling electrode circuits connectingcontrolling eledrode 

